    <div class="refentry" id="glGetActiveUniformName">
      <div class="titlepage"></div>
      <div class="refnamediv">
        <h2>Name</h2>
        <p>glGetActiveUniformName — query the name of an active uniform</p>
      </div>
      <div class="refsynopsisdiv">
        <h2>C Specification</h2>
        <div class="funcsynopsis">
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">void <strong class="fsfunc">glGetActiveUniformName</strong>(</code>
              </td>
              <td>GLuint <var class="pdparam">program</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>GLuint <var class="pdparam">uniformIndex</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>GLsizei <var class="pdparam">bufSize</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>GLsizei *<var class="pdparam">length</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>GLchar *<var class="pdparam">uniformName</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
        </div>
      </div>
      <div class="refsect1" id="parameters">
        <h2>Parameters</h2>
        <div class="variablelist">
          <dl class="variablelist">
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>program</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    Specifies the program containing the active uniform index <em class="parameter"><code>uniformIndex</code></em>.
                </p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>uniformIndex</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    Specifies the index of the active uniform whose name to query.
                </p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>bufSize</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    Specifies the size of the buffer, in units of <code class="code">GLchar</code>, of the buffer whose address is specified in <em class="parameter"><code>uniformName</code></em>.
                </p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>length</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    Specifies the address of a variable that will receive the number of characters that were or would have been written to the buffer addressed by <em class="parameter"><code>uniformName</code></em>.
                </p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>uniformName</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    Specifies the address of a buffer into which the GL will place the name of the active uniform at <em class="parameter"><code>uniformIndex</code></em> within <em class="parameter"><code>program</code></em>.
                </p>
            </dd>
          </dl>
        </div>
      </div>
      <div class="refsect1" id="description">
        <h2>Description</h2>
        <p>
            <code class="function">glGetActiveUniformName</code> returns the name of the active uniform at <em class="parameter"><code>uniformIndex</code></em> within <em class="parameter"><code>program</code></em>.
            If <em class="parameter"><code>uniformName</code></em> is not <code class="code">NULL</code>, up to <em class="parameter"><code>bufSize</code></em> characters (including a nul-terminator) will be written into
            the array whose address is specified by <em class="parameter"><code>uniformName</code></em>. If <em class="parameter"><code>length</code></em> is not <code class="code">NULL</code>, the number of characters
            that were (or would have been) written into <em class="parameter"><code>uniformName</code></em> (not including the nul-terminator) will be placed in the variable whose address
            is specified in <em class="parameter"><code>length</code></em>. If <em class="parameter"><code>length</code></em> is <code class="code">NULL</code>, no length is returned. The length of the longest uniform
            name in <em class="parameter"><code>program</code></em> is given by the value of <code class="constant">GL_ACTIVE_UNIFORM_MAX_LENGTH</code>, which can be queried with
            <a class="citerefentry" href="glGetProgram"><span class="citerefentry"><span class="refentrytitle">glGetProgram</span></span></a>.
        </p>
        <p>
            If <code class="function">glGetActiveUniformName</code> is not successful, nothing is written to <em class="parameter"><code>length</code></em> or <em class="parameter"><code>uniformName</code></em>.
        </p>
        <p>
            <em class="parameter"><code>program</code></em> must be the name of a program for which the command <a class="citerefentry" href="glLinkProgram"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a>
            has been issued in the past. It is not necessary for <em class="parameter"><code>program</code></em> to have been linked successfully. The link could have failed because
            the number of active uniforms exceeded the limit.
        </p>
        <p>
            <em class="parameter"><code>uniformIndex</code></em> must be an active uniform
            index of the program <em class="parameter"><code>program</code></em>, in the
            range zero to the value of
            <code class="constant">GL_ACTIVE_UNIFORMS</code> minus one. The value of
            <code class="constant">GL_ACTIVE_UNIFORMS</code> can be queried with
            <a class="citerefentry" href="glGetProgram"><span class="citerefentry"><span class="refentrytitle">glGetProgram</span></span></a>.
        </p>
      </div>
      <div class="refsect1" id="errors">
        <h2>Errors</h2>
        <p>
            <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>uniformIndex</code></em> is greater than or equal to the value
            of <code class="constant">GL_ACTIVE_UNIFORMS</code>.
        </p>
        <p>
            <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>bufSize</code></em> is negative.
        </p>
        <p>
            <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>program</code></em> is not the name of a program object for which
            <a class="citerefentry" href="glLinkProgram"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a> has been issued.
        </p>
      </div>
      {$pipelinestall}{$examples}
      <div class="refsect1" id="versions">
        <h2>Version Support</h2>
        <div class="informaltable">
          <table style="border-collapse: collapse; border-top: 2px solid ; border-bottom: 2px solid ; border-left: 2px solid ; border-right: 2px solid ; ">
            <colgroup>
              <col style="text-align: left; "/>
              <col style="text-align: center; " class="firstvers"/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; " class="lastvers"/>
            </colgroup>
            <thead>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; ">

            </th>
                <th style="text-align: center; border-bottom: 2px solid ; " colspan="12">
                <span class="bold"><strong>OpenGL Version</strong></span>
            </th>
              </tr>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>Function / Feature Name</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>2.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>2.1</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.1</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.2</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.3</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.1</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.2</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.3</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.4</strong></span>
            </th>
                <th style="text-align: center; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.5</strong></span>
            </th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; ">
                  <code class="function">glGetActiveUniformName</code>
                </td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; ">✔</td>
              </tr>
            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1" id="seealso">
        <h2>See Also</h2>
        <p>
            <a class="citerefentry" href="glGetActiveUniform"><span class="citerefentry"><span class="refentrytitle">glGetActiveUniform</span></span></a>,
            <a class="citerefentry" href="glGetUniformIndices"><span class="citerefentry"><span class="refentrytitle">glGetUniformIndices</span></span></a>,
            <a class="citerefentry" href="glGetProgram"><span class="citerefentry"><span class="refentrytitle">glGetProgram</span></span></a>,
            <a class="citerefentry" href="glLinkProgram"><span class="citerefentry"><span class="refentrytitle">glLinkProgram</span></span></a>
        </p>
      </div>
      <div class="refsect1" id="Copyright">
        <h2>Copyright</h2>
        <p>
            Copyright © 2010-2014 Khronos Group.
            This material may be distributed subject to the terms and conditions set forth in
            the Open Publication License, v 1.0, 8 June 1999.
            <a class="link" href="https://opencontent.org/openpub/" target="_top">https://opencontent.org/openpub/</a>.
        </p>
      </div>
    </div>
